Recently, a rechargeable battery that can be repeatedly charged and discharged has been variously used as an energy source of a wireless mobile device. In addition, the rechargeable battery has attracted attention as an energy source of an electric vehicle, a hybrid electric vehicle, and the like, which have been proposed as a solution to solve air pollution in conventional gasoline vehicles and diesel vehicles using fossil fuels. Thus, types of applications using rechargeable batteries are diversifying due to advantages of rechargeable batteries, and it is expected that rechargeable batteries will be applied to many fields and products in the future.
Such a rechargeable battery can be classified into a lithium ion battery, a lithium ion polymer battery, a lithium polymer battery, and the like depending on a configuration of an electrode and an electrolyte solution, and the use of lithium ion polymer batteries, which are easy to manufacture and have a low possibility of electrolyte leakage, is increasing. In general, the rechargeable batteries are classified into a cylindrical battery and a prismatic battery of which an electrode assembly is embedded in a cylindrical or prismatic metal can, and a pouch-type battery of which an electrode assembly is embedded in a pouch-type case of an aluminum laminate sheet.
Among them, due to high capacity of the battery, enlargement of the size of the case and processing of a thin material are attracting much attention, and accordingly, the pouch-type battery having a stacked or stacked/folded electrode assembly embedded in the pouch-type battery case of the aluminum laminate sheet has been gradually increased in usage due to low manufacturing cost, small weight, and easy shape deformation.
FIG. 1 schematically shows a conventional pouch-type battery. Referring to FIG. 1, a pouch-type rechargeable battery 10 is formed with a structure in which an electrode assembly 30 formed of a positive electrode, a negative electrode, and a separation film that is disposed between the positive electrode and the negative electrode is provided in a pouch-type battery case 20, and two electrode leads 40 and 41 that are electrically connected with positive and negative electrode tabs 31 and 32 of the electrode assembly 30 are exposed to the outside.
The battery case 20 is formed of a case main body 21, and includes a concave receiving portion 23 where the electrode assembly 30 can be received and a cover 22 connected integrally to the main body 21.
A plurality of positive electrode tabs 31 and a plurality of negative electrode tabs 32 are respectively welded to the stack-type electrode assembly 30 and thus coupled to the electrode leads 40 and 41. In addition, the electrode leads 40 and 41 are disposed at an upper end 24 of the case body 21 and an upper end of the cover 22, and insulation films 50 are respectively attached to the electrode leads 40 and 41 to prevent occurrence of a short-circuit.
Such a pouch-type rechargeable battery is widely used as an energy source for various electronic devices as well as various mobile devices. However, when a gas is generated in the charging/discharging process, the battery case is ruptured and harmful gas is leaked, thereby causing unexpected heat or explosion due to malfunction of the battery.
The rechargeable battery and a middle-sized or large-sized battery module including the rechargeable battery are provided with safety devices such as a protection circuit and a fuse for shutting off current during over-charging, over-discharging, and over-current, but cannot detect the amount of gas generated in the battery in real time. Accordingly, the time that the battery case is ruptured cannot be determined and thus the safety is significantly lowered, so that it is difficult to exhibit a desired effect.